Physical Address
304 North Cardinal St.
Dorchester Center, MA 02124
D3123-09 – Standard Test Method Technical Guide
🔬 Scope and Significance of Spiral Flow Testing
ASTM D3123-09 (Reapproved 2017) outlines a standard test method for measuring the spiral flow of low-pressure thermosetting molding compounds. Specifically designed for materials used in encapsulation and other low-pressure techniques, this method applies to compounds that are soft or very soft and intended for molding pressures under 6.9 MPa (1000 psi).
The spiral flow measurement serves as an indicator of the combined characteristics of a material’s fusion under pressure, melt viscosity, and gelation rate. This makes it an extremely valuable tool for quality control and establishing acceptance criteria for incoming materials or production batches.
📌 Standard Note: There is no known ISO equivalent to this test method. The values stated in SI units are regarded as the standard.
⚙️ Essential Apparatus and Standard Conditions
To perform this test, a transfer molding press must meet specific requirements. The press must have a minimum platen area of 150 by 150 mm (6 by 6 in.), sufficient clamp pressure to prevent flashing, and a minimum plunger speed of 25.4 mm (1 in.)/s without load. The standard also specifies the use of a specific spiral-flow mold design (Fig. 1 of the standard).
The core test conditions are strictly defined to ensure reproducibility:
| 🟦 Test Parameter | 📏 Standard Specification |
|---|---|
| Transfer Pressure | 6.9 MPa (1000 psi) |
| Mold Temperature | 423 ± 3 K (150 ± 3 °C / 302 ± 5 °F) |
| Plunger Speed (Minimum) | 25.4 mm (1 in.)/s |
The transfer pot diameter is also a critical variable. The standard permits a range of diameters but strongly recommends caution:
| 🎯 Pot Diameter Range | 📐 Metric | 📐 Imperial |
|---|---|---|
| Recommended Minimum | 31.75 mm | 1.25 in. |
| Recommended Maximum |
📥 Standard Documents Download |